Agricultural vehicle pneumatic distribution system

ABSTRACT

A pneumatic distribution system for an agricultural machine includes an air source having an outlet, an assembly configured to receive agricultural material from a material source, and a plurality of conduits. Each conduit is configured to receive an air stream from the outlet for conveying a portion of the agricultural material to at least one device associated with the agricultural machine. A first one of conduits corresponds to a first distribution line and is positioned such that the first conduit receives a first air stream from a first area of the outlet, a second one of the conduits corresponds to a second distribution line and is positioned such that the second conduit receives a second air stream from a second area of the outlet having a lower air pressure than the first area, and the first distribution line has a higher pressure drop than the second distribution line.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of and claims priority to U.S.patent application Ser. No. 15/950,497, filed Apr. 11, 2018, which is adivisional of and claims priority to U.S. patent application Ser. No.14/861,374, filed Sep. 22, 2015, the contents of which are herebyincorporated by reference in their entirety.

FIELD OF THE DESCRIPTION

The present description relates to agricultural equipment. Morespecifically, but not by limitation, the present description relates toa pneumatic distribution system for agricultural vehicles.

BACKGROUND

Agricultural vehicles or other equipment often include a pneumaticdistribution system for distributing product to one or more end points.In an air seeder, for example, an air distribution system comprises anair source that provides air flow to a plurality of distribution linesor runs. A metering system, such as a volumetric meter, can be used tometer product (e.g., seed, fertilizer, etc.) into the air flow. In oneexample, the air distribution system employs a plenum that couples theplurality of distribution lines to the output of the air source in amanner that provides equal air pressure to each distribution line.

The discussion above is merely provided for general backgroundinformation and is not intended to be used as an aid in determining thescope of the claimed subject matter.

SUMMARY

A pneumatic distribution system for an agricultural machine includes anair source having an outlet, an assembly configured to receiveagricultural material from a material source, and a plurality ofconduits. Each conduit is configured to receive an air stream from theoutlet for conveying a portion of the agricultural material to at leastone device associated with the agricultural machine. A first one ofconduits corresponds to a first distribution line and is positioned suchthat the first conduit receives a first air stream from a first area ofthe outlet, a second one of the conduits corresponds to a seconddistribution line and is positioned such that the second conduitreceives a second air stream from a second area of the outlet having alower air pressure than the first area, and the first distribution linehas a higher pressure drop than the second distribution line.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter. The claimed subject matter is not limited to implementationsthat solve any or all disadvantages noted in the background.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of one example of an agricultural vehiclewith a pneumatic distribution system for pneumatically distributingagricultural product.

FIG. 2 illustrates one example of an air source.

FIG. 3 illustrates an example air flow assembly for a pneumaticdistribution system.

FIGS. 4A and 4B illustrate an example air flow assembly for a pneumaticdistribution system.

FIGS. 5A-5D illustrate an example air flow assembly for a pneumaticdistribution system.

FIGS. 6A-6C illustrate an example air flow assembly for a pneumaticdistribution system.

FIGS. 7A-7D illustrate an example air flow assembly for a pneumaticdistribution system.

FIG. 8 illustrates a bottom perspective view of a pneumatic distributionsystem mounted on an agricultural vehicle, in one example.

FIG. 9 is a bar chart illustrating flow rates for several examplepneumatic distribution systems.

DETAILED DESCRIPTION

FIG. 1 illustrates a side view of one example of an agricultural vehiclewith a pneumatic distribution system for pneumatically (e.g., air orother gas) distributing agricultural product in the form of particulatematerial (e.g. seed, fertilizer, etc.). In the illustrated example, thevehicle comprises an air seeder 10 that pneumatically delivers seedand/or fertilizer to ground engaging openers. Of course, a pneumaticdistribution system can be utilized with other types of vehicles aswell.

Seeder 10 comprises a seed cart 11 towed between, for example, a tractor(not shown) and a tilling implement 12. The seed cart 11 also includes aframe 14 to which product tanks 16 and wheels 18 are mounted. Eachproduct tank 16 includes an associated metering system 20 at its lowerend for controlled feeding of a product into a pneumatic distributionsystem 22. The metering system 20, is adjacent to a discharge end of aproduct tank 16. The tilling implement 12, towed behind the seed cart11, comprises a frame 30 to which ground openers 32 are mounted.Incorporation of seed row finishing equipment, such as closing wheels34, can also be utilized, in one example.

Pneumatic distribution system 22 includes an air source 36, such as, butnot limited to, a fan, blower, compressor, and/or pump. In theillustrated example, air source 36 comprises a centrifugal fan (alsoreferred to as centrifugal fan 36) connected to a plenum 38, which inturn is connected through one or more conduits to one or more primarydistribution manifolds 24. Each manifold 24 is configured to receiveproduct from one of product tanks 16 that is metered through meteringsystem 20. In one example, metering system 20 comprises one or morevolumetric meters that volumetrically meters product into distributionsystem 22.

Each individual passage in the primary distribution manifold 24 isconnected by a distribution line 40 to a riser tube 42. However, whileonly one riser tube 42 is shown in FIG. 1, in another example, multipleriser tubes 42 can be utilized. Each riser tube 42 is, in turn, coupledto a secondary distribution header 44. One or more distribution lines 46connect the secondary distribution header 44 to seed boots (not shown)mounted on the ground openers 32 to deliver product (e.g. seed orfertilizer) to a furrow formed by the openers 32.

While seeder 10 of FIG. 1 is shown as a separate seed cart 11 connectedto tilling implement 12, in one example, the product tank 16, meteringsystem 20 and pneumatic distribution system 22 can be mounted on thesame frame as the ground openers 32. Further, while air source 36 isdescribed herein as providing a source of air, source 36 can beconfigured to provide a flow of other types of distribution gasses aswell.

FIG. 2 illustrate one example of centrifugal fan 36. As shown in FIG. 2,which is a perspective of fan 36, an inlet port 50 receives air(generally represented by arrow 51), which is moved through a housing 52to an outlet 54 by impellers or rotating blades that rotate about a fanaxis 56.

The air exits outlet 54 (generally represented by arrow 55) withdifferent air pressures that define a pressure gradient across outlet54. That is, depending on the configuration of the fan, some areas orpressure zones have higher pressures than other areas in outlet 54. Inthe example centrifugal fan 36, a pressure gradient is defined along apressure axis 58, where high pressure areas 60 are located near an outerperiphery 62 (i.e., further away from axis 56) and low pressure areas 64are located more closely to axis 56. While the air source is illustratedas a centrifugal fan in FIGS. 1 and 2, other types of air sources can beutilized that have pressure gradients.

In one example air distribution system design, a large plenum box isaffixed to the outlet of the air source to mitigate the differentpressures along the pressure gradient, thereby providing substantiallyequal pressures to the distribution paths. For example, the plenum boxcan be configured such that static pressure at each primary outlet ofthe plenum is substantially equal.

However, in some applications, the lengths of the distribution lines aresignificantly different. For example, referring again to air seeder 10,some distribution lines 40 have different lengths from the air source 36depending on the particular endpoints (e.g., row unit). In one example,distribution lines 40 can vary up to 30 feet, or more. For instance, adistribution line to an inner row unit can be 30 feet long, whereas adistribution line to an outer row unit can be 50 feet long. This, ofcourse, is an example only.

In any case, some distribution lines 40 have different pressure dropsdue to the length differences, or other factors. This results in anuneven pressure loss, and different volumetric flow rates at the endpoints, which can affect seed spacing, yields, etc. In one attempt toprovide equal flow rates to all row units (i.e., to limit row to rowvariation in seed application), undesired pressure loss variationbetween distribution lines is reduced by restricting flow in the shorterlines in order to equalize the pressure loss across all distributionlines. For example, in one implementation a restricting damper, plate,orifice, or other device is placed in the shorter distribution lines sothat the shorter distribution lines have a similar pressure dropcompared to the longer distribution lines. However, such a configurationrestricts commodity conveyance, decreases the overall efficiency of thefan, and increases the overall energy consumption and requirements toachieve a desired volumetric flow rate.

The present disclosure provides a pneumatic distribution system forpneumatically distributing material in an agricultural vehicle. Thepneumatic distribution system comprises an air source having an outletwith different air pressures defining a pressure gradient across theoutlet, and a plurality of inlet ports configured to receive air fromthe outlet for a plurality of distribution streams, comprising at leasta first distribution stream with a first pressure loss value and asecond distribution stream with a second pressure loss value that isgreater than the first pressure loss value.

In one example, the inlet ports for the first and second distributionstreams are located relative to the pressure gradient such that thesecond distribution stream receives a higher air pressure than the firstdistribution stream. In one example, the air pressure at the inlet forthe second distribution stream is at least two times greater than theair pressure at the inlet for the first distribution stream. In oneexample, the air pressure at the inlet for the second distributionstream is at least three times greater than the air pressure at theinlet for the first distribution stream. In one example, the airpressure at the inlet for the second distribution stream is at leastfour times greater than the air pressure at the inlet for the firstdistribution stream. In one example, the air pressure at the inlet forthe second distribution stream is at least five times greater than theair pressure at the inlet for the first distribution stream.

In one example, the plurality of distribution streams comprises aplurality of lines, or runs, to row units on an air seeder. As usedherein, a “line” refers to a channel or path to an end point. Forinstance, a line can provide an air flow path to one or more row units.Further, a line can be formed by a plurality of separate elementsconnected together. For instance, a given line can comprise separateconduit(s), tube(s), manifold(s), meter(s), row unit(s), etc., coupledtogether to form a single distribution path from the air source to anend point.

FIG. 3 illustrates one example of an air flow assembly 200 for use witha pneumatic distribution system. Assembly 200 is removably coupled to anair source 201 (e.g. fan 36), having a housing 202, at a connectioninterface 204. In one example, housing 202 is substantially similar tohousing 52 illustrated in FIG. 2. While connection interfaces (e.g.,interface 204) are herein illustrated as substantially flat or planar(also referred to as a connection plane—e.g., connection interface 204),in other examples a connection interface can be non-planar.

Assembly 200 includes a fixed, inflexible body portion 206, and aplurality of conduits 210 coupled to and extending from portion 206.Fixed portion 206 is coupled (removably or otherwise) on one end tohousing 202 at connection interface 204 and, on a second end, to theplurality of conduits 212. Portion 206 and conduits 210 form a pluralityof air flow paths for a respective air flow (generally represented byarrows 208) generated by source 201. Each air flow 208 forms adistribution stream.

As discussed in further detail below, assembly 200 includes a pluralityof inlet ports configured to receive the air, from the outlet of source201 at connection interface 204, for the plurality of distributionstreams. Each distribution stream is provide to an end point (e.g., arow unit, meter, etc.) using one or more conduits, or other element(s).In one example, conduits 210 convey the air to a volumetric meteringsystem (e.g., manifold 24 of system 20 illustrated in FIG. 1).

In the illustrated example, the inlet ports receive a section of thepressure gradient present at the outlet of source 201 such that thedistribution streams having higher pressure drops receive higher airpressure from source 201 than distribution streams having lower pressuredrops.

FIGS. 4A and 4B (collectively referred to as FIG. 4) illustrate oneexample of portion 206. At the connection interface 204, portion 206includes a plurality of inlet apertures 212. Portion 206 also includes aplurality of outlet apertures 214 at a conduit connection side orinterface 222, and a plurality of passageways 224, 226, 228, and 230formed between the inlet and outlet apertures. Outlet apertures 214 areconfigured to receive and fluidically couple to conduits 210 (not shownin FIG. 4). It is noted that while the example of FIG. 4 illustratesapertures arranged in a symmetrical four by two configuration for eightflow paths, portion 206 can be configured in another of a number of ways(including asymmetrically), for any number of flow paths.

In the illustrated example, fixed portion 206 is configured such thatthe air from the air source outlet is segmented at the connectioninterface 204. That is, the inlet ports formed by apertures 212 arelocated at, or in close proximity to connection interface 204, and thusthe air source outlet. This example configuration advantageously obtainsair flow streams with a maximum, or near maximum, pressure differentialbetween lines. That is, this configuration utilizes the pressuregradient at the air source outlet to distribution streams of differingair pressures.

As shown in FIGS. 3 and 4, passageways 224 are formed by apertures 212that are positioned to receive air from a relatively low pressure area(e.g., lower pressure area 64 shown in FIG. 2) and passageways 230 areformed by apertures 212 that are positioned to receive air from arelatively high pressure area (e.g., high pressure areas 60 shown inFIG. 2). Passageways 226 and 228 are positioned between passageways 224and 230, and are configured to receive air from pressure areas that arebetween the low and high pressure areas. In other words, passageways 230each have a substantially similar air pressure, which is greater thanthe air pressure in passageways 228. Likewise, passageways 228 each havea substantially similar air pressure, which is greater than the airpressure in passageways 226. Likewise, passageways 226 each have asubstantially similar air pressure, which is greater than the airpressure in passageways 224. As such, in the illustrated example, thepassageways 224, 226, 228, and 230 that form the inlets to thedistribution streams are arranged in continuum with passageways 224receive the lowest pressure, passageways 230 receive the highestpressure, and passageways 226 and 228 are arranged in the continuumbetween the lowest and highest pressures.

Accordingly, conduits 210 are connected to portion 206 based on therelative pressure drops in the distribution streams provided by thoseconducts. For example, conduits 210 are connected to portion 206 suchthat longer distribution lines receive air from the outer diameter ofsource 201 (i.e., air with the highest dynamic pressure). The shortestdistribution lines, on the other hand, receive air from an area of theair source outlet that is closest to the fan axis (i.e., air with thelowest dynamic pressure). The coefficient of variation between thedistribution line air pressures can be adjusted by the position of theinlet ports relative to the outlet pressure gradient and/or the size ofthe inlet ports. For example, an air seeder implementation with asmaller distribution line length variation (i.e., a shorter implementwidth) utilizes a smaller pressure variation between lines than an airseeder implementation with a larger distribution line length variation.

Accordingly, in the illustrated example, configuring the distributionlines to receive air flows from the air source at different pressurevalues facilitates substantially balanced outlet pressures and flowrates among different distribution line lengths without increasing powerconsumption by the air source. Additionally, the example air flowassembly can reduce space requirements compared to a large plenum box,as discussed above.

Further, it is noted that the length of passageways 224, 226, 228, and230 through portion 206 can be the same or different. In the example ofFIG. 4, air source connection interface 204 is oriented at an angle withrespect to a conduit connection interface 222. In another example,interfaces 204 and 222 can be substantially parallel to one another.

FIGS. 5A-5D (collectively referred to as FIG. 5) illustrate anotherexample of a fixed portion 240 for an air flow assembly. Fixed portion240 comprises eight air flow paths for respective air flows (generallyrepresented in FIG. 5 by arrows 208), arranged in a “T-shaped”orientation. The T-shaped orientation comprises of a four by onearrangement 241 coupled to a two by two arrangement 243. The fixedportion 240 comprises an air source connection interface or plane 204configured to couple to an air source, and a conduit connectioninterface or plane 222 configured to couple to a plurality of conduits(not shown in FIG. 5).

As shown in FIG. 5B, portion 240 comprises a plurality of passageways242, 244, and 246 from between corresponding inlet and outlet apertures.The inlet apertures at air source connection interface 204 aresubstantially rectangular in shape, and have differing sizes. In anotherexample, the inlet apertures can be substantially cylindrical and/orhave similar sizes.

In FIGS. 5C and 5D, which are side and top views of portion 240,respectively, passageways 242, 244, and 246 are shown in phantom. Aplurality of different inlet pressure zones present along connectioninterface 204 are utilized to form air flows 208 of differing pressures.In one example, the highest pressure air flows 208 originate fromconnection ports 246, and the lowest pressure air flow 208 originatefrom passageways 242.

Referring again to FIG. 3, in one example, conduits 210 are formed offlexible material(s) such that they can be maneuvered around structuralor other components of the agricultural vehicle (i.e., seeder 10). Inone example, conduits 210 comprise a substantially rigid portionsmovably coupled together by a plurality of joints.

FIGS. 6A-6C (collectively referred to as FIG. 6) illustrate anotherexample of an air flow assembly 300 coupled to an air source 301 (e.g.,fan 36), having a housing 302, at an air source connection interface352. Assembly 300 includes a fixed portion 350 coupled to a plurality ofconduits 362 at a conduit connection interface. Air source 301, in oneexample, is substantially similar to source 36.

As shown in FIGS. 6B and 6C, which illustrate front and rear perspectiveviews, respectively, fixed portion 350 comprises a plurality ofpassageways 354, 356, 358, and 360 that separate air flows (generallyrepresented by arrows 308) at or in close proximity to the air sourceoutlet at interface 352, where the pressure gradient is greatest.

Passageways 354 draw air from the air source outlet that has a relativehighest pressure, and passageways 360 draw air from the air sourceoutlet that has the relative lowest pressure. The inlet apertures topassageways 354, 356, 358, and 360 are located along or in closeproximity to interface 352. In the illustrated example, the inletapertures have different cross-sectional areas. In another example, thecross-sectional areas can be substantially similar. The sizes of eachinlet aperture can be configured based on the require air flow andpressure drops in the distribution lines.

FIGS. 7A-7D (collectively referred to as FIG. 7) illustrate anotherexample of an air flow assembly 400 configured to be coupled to an airsource (e.g., fan 36). FIGS. 7A and 7B are a side view andcross-sectional perspectival view, respectively. FIGS. 7C and 7D are endand exploded views, respectively.

As shown in FIG. 7, assembly 400 includes a mounting body 402 formounting to the air source at an air source connection interface 404 anda conduit interface plate 406 configured to receive a plurality ofconduits (not shown in FIG. 7) that form air flow paths for respectiveair flows (generally represented by arrows 408). Assembly 400 includes apremixing chamber or space 410 between the connection interface 404 andinlet ports 412, 414, and 416 for the distribution streams.

In the illustrated example, premixing chamber 410 facilitates premixingof the air from the air source outlet before entering, and beingsegmented by, ports 412, 414, and 416. This premixing reduces thepressure gradient to some extent (i.e., the pressures in thedistribution streams are somewhat equalized). In other words, thepressure gradient at interface 404 is different than the pressuregradient at ports 412, 414, and 416. The amount that the pressuregradient is reduced can depend on the size of the premixing chamber 410and distance between connection interface 404 and ports 412, 414, and416. Premixing can be advantageous in implementations with a smallerdistribution line length variation. To illustrate, in one example, thedifference in air pressure between ports 412 and 416 is less than thedifference in air pressure between passageways 226 and 228 in FIG. 4.

In the illustrated example, inlet ports 412, 414, and 416 are arrangedin a symmetrical three by three configuration. Some or all of the inletports are fluidically coupled to conduits that provide productdistribution lines. One or more of the inlet ports can be fluidicallycoupled to conduit(s) that provide air for other purposes. For example,inlet port 418 comprises a tank pressurization port that is coupled to aconduit that provides pressuring air for a tank (e.g., a seed tank,etc.). It is noted that other symmetrical or nonsymmetricalconfigurations can be utilized.

As shown in FIG. 7D, assembly 400 comprises one or more sealinginterfaces, formed by gasket(s), o-ring(s), and/or another suitablesealing mechanism(s). For example, sealing interfaces 420 and 422, suchas rubber gaskets, provided between body 402 and the air source, andbetween body 402 and plate 406, respectively. A cover 424 is removablycoupled to body 402 using a latch 426. Cover 424 is positioned to retainplate 406 proximate premixing chamber 410.

In one example, an orifice plate 428 is positioned proximate conduitconnection plate 406. Orifice plate 428 includes a plurality orificesaligned with the ports formed in plate 406. Some or all of the orificeshave a substantially similar size in relation to the cross-section ofthe ports in plate 406. However, one or more of the orifices in orificeplate 428 can have a reduced size to restrict the air flow through thecorresponding port in plate 406. In the example of FIG. 7D, an orifice430 in plate 428 has a substantially smaller size than the correspondingorifice 432 in plate 406 to form pressurizing port 418.

In one example, orifice plate 428 is formed of metal (e.g., steel,etc.). The other components of assembly 400 can be formed of anysuitable material(s) as well. In one example, body 402 conduitconnection plate 406 and/or cover 424 can also be formed of plastic(e.g., polyethylene, etc.) and/or metal.

It is noted that, in one example, each of the air flow assembliesillustrated in FIGS. 3-7 are configured for use with a same or similarair source. As such, the air flow assemblies can be easily interchangedat the air source connection plane (e.g., interfaces 204, 352, 404,etc.) based on the particular application and distribution requirements(e.g., different crops or seeding rates, different seeding implementwidths, etc.).

FIG. 8 illustrates a bottom perspective view of a pneumatic distributionsystem 500 mounted on an agricultural vehicle 502, in one example.System 500 includes a plurality of air sources 504 and 506 (e.g.,centrifugal fans). A first air flow assembly 508 is coupled to airsource 504 and a second air flow assembly 510 is coupled to air source506. A first set of conduits 512 couple each air flow assembly 508, 510to a metering system 514. In FIG. 8, the conduits coupled to assembly508 have been omitted for illustration purposes. A second set ofconduits 516 provide distribution paths from the metering system 514.

For sake of illustration, but not by limitation, FIG. 9 is a bar chartillustrating flow rates, in cubic feet per minute (CFM), for severalexample pneumatic distribution systems that utilize a substantiallysimilar air source. A first group of bars 602 represent a firstdistribution line length (e.g., fifty eight foot distribution line fromfan outlet to row unit), a second group of bars 604 represent a seconddistribution line length (e.g., forty nine foot distribution line fromfan outlet to row unit), a third group of bars 606 represent a thirddistribution line length (e.g., thirty seven foot distribution line fromfan outlet to row unit), and a fourth group of bars 608 represent afourth distribution line length (e.g., twenty three foot distributionline from fan outlet to row unit).

Each group of bars includes a first bar 610 and a second bar 630. Thefirst bar 610 represents a first distribution system that utilizes alarge plenum box that equalizes air pressures at the distribution lineinlets through substantial mixing of the air prior to segmentation intothe individual distribution lines. The second bar 630 represents asecond distribution system that utilizes an air flow assemblysubstantially similar to the example shown in FIG. 3.

As shown in FIG. 9, first distribution system exhibits a greaterdifference in flow rate between the longest and shorts distributionlines. That is, the flow rate in the shortest distribution line isapproximately sixty-three percent of the flow rate in the longestdistribution line. However, the flow rates in the second distributionsystem is significantly more similar (i.e., flow rates in the shortestdistribution lines are eighty-six percent compared to the longestdistribution lines). Additionally, compared to the first distributionsystem, the example second distribution system can reduce pressure lossby approximately forty percent, and reduce housing cut-off flowcirculation, which can improve fan efficiency.

It should also be noted that the different examples described herein canbe combined in different ways. That is, parts of one or more examplescan be combined with parts of one or more other examples. All of this iscontemplated herein.

Example 1 is a pneumatic distribution system for pneumaticallydistributing material in an agricultural vehicle, the pneumaticdistribution system comprising an air source having an outlet withdifferent air pressures defining a pressure gradient across the outlet,and a plurality of inlet ports configured to receive air from the outletfor a plurality of distribution streams, comprising at least a firstdistribution stream with a first pressure loss value and a seconddistribution stream with a second pressure loss value that is greaterthan the first pressure loss value, wherein the inlet ports for thefirst and second distribution streams are located relative to thepressure gradient such that the second distribution stream receives ahigher air pressure than the first distribution stream.

Example 2 is the pneumatic distribution system of any or all previousexamples, wherein the air source comprises a centrifugal fan.

Example 3 is the pneumatic distribution system of any or all previousexamples, wherein the air pressure at each inlet port is proportional tothe pressure loss value of the corresponding distribution stream.

Example 4 is the pneumatic distribution system of any or all previousexamples, wherein the plurality of distribution streams comprise aplurality of lines that distribute air from the outlet to a plurality ofend points.

Example 5 is the pneumatic distribution system of any or all previousexamples, wherein each of the plurality of inlet ports is configured toreceive air along the pressure gradient such that, at the plurality ofend points, the air flow rates in the plurality of distribution streamsare substantially equal.

Example 6 is the pneumatic distribution system of any or all previousexamples, wherein each of the lines comprises a separate conduitfluidically coupled to one of the inlet ports.

Example 7 is the pneumatic distribution system of any or all previousexamples, wherein the agricultural vehicle comprises an air seeder, andthe plurality of end points comprise row units on the air seeder.

Example 8 is the pneumatic distribution system of any or all previousexamples, wherein each conduit couples the respective inlet port to ametering system configured to meter material into the respectivedistribution stream.

Example 9 is the pneumatic distribution system of any or all previousexamples, wherein the metering system comprises a volumetric meter.

Example 10 is the pneumatic distribution system of any or all previousexamples, wherein the inlet ports for the first and second distributionstreams have a substantially similar cross-sectional area.

Example 11 is the pneumatic distribution system of any or all previousexamples, wherein the inlet ports for the first and second distributionstreams have different cross-sectional areas.

Example 12 is the pneumatic distribution system of any or all previousexamples, wherein the plurality of inlet ports are fluidically coupleddirectly to the outlet.

Example 13 is the pneumatic distribution system of any or all previousexamples, wherein the plurality of inlet ports are spaced apart from theoutlet.

Example 14 is the pneumatic distribution system of any or all previousexamples further comprising a plenum chamber that is located between theoutlet and the plurality of inlet ports and configured to receive theair from the outlet for the plurality of distribution streams.

Example 15 is the pneumatic distribution system of any or all previousexamples, wherein the inlet ports for the first and second distributionstreams are fluidically coupled to the plenum chamber.

Example 16 is an agricultural implement comprising a product source, ametering system configured to meter product from the product source, anda pneumatic distribution system configured to pneumatically distributethe metered product to a plurality of end points on the agriculturalimplement, the pneumatic distribution system comprising an air sourcehaving an outlet with different air pressure zones defining a pressuregradient across the outlet, and

a plurality of distribution lines configured to provide air streams tothe plurality of end points, the plurality of distribution linescomprising at least a first distribution line and a second distributionline that has longer length than the first distribution line, whereinthe second distribution line is configured to receive higher airpressure compared to the first distribution line.

Example 17 is the agricultural implement of any or all previousexamples, wherein the agricultural vehicle comprises an air seeder, theair source comprises a centrifugal fan, and the plurality of end pointscomprise row units on the air seeder.

Example 18 is the agricultural implement of any or all previousexamples, wherein the outlet comprises a fan axis, and an inlet for thesecond distribution line is located further away from the fan axis thanan inlet for the first distribution line.

Example 19 is an agricultural pneumatic distribution system comprising afan assembly having an outlet, and a plurality of conduits, eachconfigured to receive an air stream for conveying an agriculturalmaterial to an end point, wherein a first one of conduits is positionedsuch that it receives a first air stream from a high pressure area ofthe outlet and a second one of the conduits is positioned such that itreceives a second air stream from a low pressure area along the pressuregradient, wherein the first conduit is associated with a distributionline having a higher pressure drop than a distribution line associatedwith the second conduit.

Example 20 is the pneumatic distribution system of any or all previousexamples, wherein the fan assembly comprises a centrifugal fan having afan axis, and wherein a first inlet for the first conduit is locatedfurther away from the fan axis than a second inlet for the secondconduit.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. An agricultural pneumatic distribution system comprising: an air source having an outlet with different air pressures defining a pressure gradient across the outlet; at least first and second distribution lines, each distribution line comprising one or more conduits configured to convey air to a corresponding end point component of the distribution line; and a housing coupled proximate the outlet of the air source and comprising of at least: a first passageway comprising: a first inlet aperture configured to receive air at a first air pressure from the air source, and a first outlet aperture fluidically coupled to the first distribution line, the first distribution line having a first pressure drop between the first passageway and the corresponding end point component of the first distribution line; and a second passageway, separate from the first passageway, comprising: a second inlet aperture configured to receive air at a second air pressure from the air source that is less than the first air pressure, and a second outlet aperture fluidically coupled to the second distribution line, the second distribution line having a second pressure drop, that is lower than the first pressure drop, between the second passageway and the corresponding end point component of the second distribution.
 2. The agricultural pneumatic distribution system of claim 1, wherein the housing comprises: a plurality of passageways, each having an inlet aperture facing the outlet of the air source and configured to provide the air from the air source to a different distribution line.
 3. The agricultural pneumatic distribution system of claim 2, wherein the plurality of passageways are arranged symmetrically.
 4. The agricultural pneumatic distribution system of claim 2, wherein the plurality of passageways are arranged in a T-shaped orientation.
 5. The agricultural pneumatic distribution system of claim 2, wherein the plurality of inlet apertures are substantially rectangular in shape and have different cross-sectional areas from each other.
 6. The agricultural pneumatic distribution system of claim 1, wherein the air source comprises a centrifugal fan.
 7. The agricultural pneumatic distribution system of claim 6, wherein the centrifugal fan comprises a rotation axis, and the second inlet aperture is located closer to the rotation axis than the first inlet aperture.
 8. The agricultural pneumatic distribution system of claim 2, wherein the housing comprises a rigid body supporting the inlet apertures and outlet apertures, and the inlet apertures are positioned proximate the outlet of the air source.
 9. An agricultural implement comprising: a metering system configured to meter product from a product source; and an agricultural pneumatic distribution system comprising: an air source having an outlet with different air pressures defining a pressure gradient across the outlet; a plurality of conduits for distribution lines; and a fixed portion proximate the outlet of the air source and comprising a plurality of inlet apertures, each inlet aperture configured to receive a portion of air from the outlet and convey the portion of air to a corresponding one of the of conduits, wherein the plurality of inlet apertures comprises a first inlet aperture configured to receive a higher air pressure that is conveyed to a first one of the conduits compared to a second inlet aperture corresponding to a second one of the conduits, and the first conduit is associated with a first distribution line having a higher pressure drop than a second distribution line associated with the second conduit.
 10. The agricultural pneumatic distribution system of claim 9, wherein the fixed portion comprises: a plurality of passageways configured to provide the air from the plurality of inlet apertures to the plurality of conduits, and wherein the plurality of passageways comprise a first passageway configured to provide the higher air pressure for the first one of the conduits and a second passageway configured to provide the lower air pressure for the second one of the conduits.
 11. The agricultural implement of claim 10, wherein the plurality of passageways are arranged symmetrically.
 12. The agricultural implement of claim 10, wherein the plurality of passageways are arranged in a T-shaped orientation.
 13. The agricultural implement of claim 10, wherein the plurality of inlet apertures are substantially rectangular in shape and have different cross-sectional areas from each other.
 14. The agricultural implement of claim 10, wherein the air source comprises a centrifugal fan.
 15. The agricultural implement of claim 14, wherein the centrifugal fan comprises a rotation axis, and the second inlet aperture is located closer to the rotation axis than the first inlet aperture.
 16. The agricultural implement of claim 9, wherein the fixed portion comprises a rigid body supporting the inlet apertures. 